Knowledge of the intensity of the Earth's magnetic field throughout geological time can deliver a wealth of information regarding the development of the planet. The nature of the geomagnetic field is dependent on processes that occur deep in the Earth's core. By analysing long period changes in geomagnetic field intensity inferences can be made about conditions in the Earth's interior far back into Earth history. The microwave palaeointensity technique is a relatively recent addition to palaeomagnetic investigation. High-frequency microwaves, which are resonant with the constituent magnetic system of a rock, are used to isolate and progressively remove the magnetisation of samples acquired at the time of formation in a controlled manner. By exciting the magnetic system directly, thermal-type experiments can be conducted, whilst minimising the risk of chemical alteration, which is a major cause of experimental failure.